Radiant energy control device



Jan. 23, 1951 J. 5. HERSON RADIANT ENERGY CONTROL DEVICE Filed July 16, 1945 2 Sheets-Sheet 2 M 0 w e f Wm INVENTOR. J4606 6? #6954 Patented Jan. 23, 1 951 UNITED liDATENT OFFICE RADIANT ENERGY CONTROL DEVICE I Jacob S. Herson, Dayton, Ohio Application-July 16,- 1945, Serial No. 605,450

2 Claims. (01. 250-1) (Granted under the act of March 3, 1883, as amended dipril 30; 1928; 370'0. G. 757) 1 The-invention described herein may be manufactured and used by or for the Government for governmental purposes without payment to me of any royalty thereon.

The present invention relates to radiant energy control devices of the thermo-pneumatic type.

The fundamental receivingunit is ifully described in the patent to Hall, No. 2,115.573, granted April 26, 1938 and further reference thereto in the description of this invention will be made solely to facilitate such description. 'The fundamental unit, hereinafter referred tdaas cell, comprises a chamber enclosing a body of dark; heat-absorbing substance which is sensitive to radiant energy over a wide band of frequencies,

together with a member such as a diaphragm which is influenced by the pressure changes induced by the radiant energy absorbed by the dark substance. In the cell utilizedfwith this invention, the radiant energy causesadisplacement of one flexible electrode 'with respect to a second fixed electrode, both electrodesbeing of metallic or metalized substance and separated by air or gas dielectric. The separation of the two elet'itrodesby the dielectric efiectively constitutes acondenser whose capacitance varies under' the influence of incident radiated energy.

T-li'epatent to Hall relates to use xii-the cell as a receiver for detection of bodies which are of .measurement of radiation from a distant emitter s'uchas an aircraft or other metallic'substance and as a signalling device; The novel" features of tliisinvention is th provision of a system whereby the overall sensitivity is increased by conversion of theradi'ant energy into audible and visible signals, and whereby the relative direction of the arrival of the radiated energyis indicated.-

It is, therefore; an object "of 'this'dnvention to" provide c'ircuitmean's' wherebyth" riation' of the capacitance of the-cell is converted into audible signals. 5 t

' Another object is to provide circuit means for the conversion of the radiated energy into visible 1 '**Afuflhrbbiekrtisto providefci'r means for indicating I: the relative direction of he arrivalf e 'ad 'ed. 'a rstill further object is to prov in a-radiant energy signal deriving system the rnethod of converting received radiant energy into' signal indieating energy to actuatesignal indicators. -Other ebjects and. features-of novelty will ap e'nt'. 11 rom; the} renewi g ees rgpuoha d} H16 Initiated "draliliingsf 115being undef 2 stood, however, that the invention is not limited in any way by such description and drawings or otherwise than by the appended claims. 7

Referring to the drawings in which similar reference numerals refer to like parts, Fig. 1 is a block diagram illustrating the interconnection of the components of one form or this invention with the radiant energy receiving cell; Fig. 2 is a schematic diagram of one form of the visual indicator portion of this invention; Fig. 3 is a schematic diagram of an alternate form of the visual indicator portion of this inven-f tion, and; Fig. 4 is a block diagram illustrating a multiple channel arrangement of the components of this invention for indicating the relative direction of arrival of radiated energy. Referring now to Figfil of the drawings, radiated energy from any distant source incident upon lens I which is transparent to the received radiation, is concentrated on the black body contained in cellf l2 causing a displacement of the metalized membrane l I with respect to flat metal plate I3 thus varying the capaci'-' tance formed by the proximity of metalized mem-'' brane 'H to metal plate 43, with air as the dig electric. This effected capacitor is connected to tank circuit l4 and forms a part thereof to de termine the frequency of oscillation of radiofrequency varying oscillator l5. Radio-fre-- quency fixed oscillator It is adjusted by means of variable capacitor I! to zero beat with radio frequency oscillator 15 in'the absence of any coming radiant energy. The output of oscillator I5 is feddirectly to mixer stage l8 and the output of oscillator I6 is fed} through isolating am- I plifier stage l9 to mixer ';stage 18 to derive the I diiierence frequency which is audible, isolating amplifier [9 being utilized to prevent interaction} (locking) by oscillator with oscillator It. The output of mixer stage I8 is fed to and amplified by audio amplifier 20. The audio output from amplifier 20 is made audible by loud speaker 2L"- Single-pole-double-throw switch 22 is employed to switch the output from mixed l8 to' visual indi cator 23 if visual indication of the presence orradiated energy from any source within the field of lens l0 and cell I2 is desired. i

The operation is as "follows: With the radiant,

energy receiving cell in a quiescent state, the fixed oscillator is adjusted to zero beat with the radio-frequency varying '3' scillator; Radiation froni any target within; the-' range efthis devie causes a change of-capaeitarice iii-the c ll afid' therefore a change of frequency of the radiofrequency varying oscillator, thus producing a beat note in the mixer stage of a frequency equal to the difference between the frequencies of the radio-frequency varying oscillator and the fixed 5 oscillator. The output from the mixer is made audible bymeans of a loud speaker orearphones;

Referringnow to Fig.2 of the drawings, when radiated energy has, as previously described, been received, and switch 22 is thrown to visual indir- H1 cator position, the output circuit of the mixer stage is inductively coupled throughtransformer 24 to the control grid of amplifier tube 25. The;

output circuit of this tube is then capacitively coupled to the control grid of :pentddetfrequencyvlr,:v

counting tube 26. Condenser 21 is normally charged to the value of the high voltage plate" supply since tube 26 is biased5to-1cut-offi.1-Tube. 26 conducts only during the positive halfbycldi of the input signal, during which time, tube 26 presents a discharge pathfor condenser 21.- Dun ing the negative half cycle of the inputsignaL:

condenser 21 charges again, the charge anddischarge'cycle beingrepeated. every cycle of-the incoming signal. Diode-tube 2-8 is .placed in 95 plate currentof tube 30 and the-voltage drop across .resistor 32 below-the required voltage for firin n on tube 33. Inthe presence of an input signal on the grid oftube-3il, the plate current, rises ,during-eachpositive half cycle sufficiently toraise the voltage drop across resistor 32 above 40.

the firing point of neon tube 33 so'that condenser 34 which -isin parallel with and charged to the same-voltage asthe-voltage across resistor-:32

causes neon tube33 to fire and form-adischargepath; for .condenser .34, thus :providingvisual in,

di'cation. of the presence of a radiating body. The

rate .ofn'charge and. .discharge of condenser v3 t is determined by the constants ofthe circuit elements associated with the plate circuit of tube30A Another form of visual indicator than the one 60 illustrated in Fig. 2 is shown in Fig. 3 of the draw- .ings. Referring now to Fig.- 3 of the drawingsthe input signal from mixer I8 (shownin Fig. .1) isv capacitively coupled to thecontrol grid .of gas tube 35.- The gridand cathode electrodes of gas.

tube 35 are -so connected to bleeder resistor 35- that the'grid is sufiiciently negative with respect to the cathode to maintain-tube35 normally-non- ;conductingz: In the presence of a signal, the -out--;-

put of .mixer l8 raises :thegrid voltage of tube.

-35:during;the first positive half-cycle of the input signalcausing tube 35 to conduct.v Condenser 39 .isconnected between ground and the high voltage supply and is normally-maintained in a'charged ;condition by the highvoltage supply. When tube 05.;

. axis-triggered into conductance by theincoming.

-si-g al ,condenser.=,:39 is;.discharged.:. through..the...

path} 'forn ed-gby saidtube 135 therebymaintaining a high voltage on the plate ofsaidtube 35.. The

. discharge of condenser -39-serves tormaintain-re- 70.

.lay'coil 31 in an energized condition-for a prede- .termined periodof time aften-the beginningof theeconductingmeriod. of .tube .35, dependinggon.

The-charge pulses develop-1a 30,

bell or operates any desired auxiliary control citcuit. After condenser 39 is fully discharged, tube 35 ceases to conduct and condenser 39 is immediately charged up until the next incoming positive half cycle of the signal from mixer I8 causes tube 35 to conduct again and the cycle is repeated.

. Thescape of this inventionrmay. bewextended' to -indicate the relative direction of arrival of radiation. This may be accomplished by employ- .ing several parallel detector channels, each channel being structurally similar to the detector 11- lustra'tedin One form of such an arrangement of detector channels is illustrated by Fig. 4. Referring now to Fig. 4 of this invention, the referencexxnumeralmlfl represents a condensing lens. An. assembly 40 is made in one structure ofth'e equivalent of three single "cells I2, I2 and LI Z'sJrBSpectiYelyya single "cell I2 being used as-fillustrated:in'Fig. 1. Radiation from a target located on the axis of lens I0 is concentrated on middle -cell;. I2 of assembly Land-radiations stages I8, I8 and I8! each similar to mixerstage I 8, illustrated, in Figs 1.-

frequency to be fedztoone of-indicators 23, 223? and 23'. depending-onwhether the source of r diated-energy is directly ahead, to the right -or' .to the left of lens I0, thus indicating :the relative .direction of arrival ofcradiationa It.- is clear. that;

the number .Of circuit channels canbesincreased. if desirable.

the axis of lens I 0,:if this-invention is used in aira craft.

This type .of multiple channel. detector may be.=- used .for automatically 'r'steering, an aircraft ore robot; in such aamanner-;as .-to.fhomel on=xth source of.radiation.;, l l

Having thus described my invention,'I claim: 1.. In a" radiant energyrdetecting device e1 n ploying detecting cells of. the type in which radi-.

ant energy received by thei'cell causes a capacity changepa plurality of such cells arranged along, one. .or more axes, means-for concentrating reeceived radiant energy on certain; of said cells de-,

pending on the .directiomof-.thesourcaof radiant energy; from the detecting device,- a variable fre cells tocontrol theirequencies of said oscillators, a .beat freq-uency' oscillator, means associated-with the output-circuit of each of said variable oscil-'.

lators for combining its frequency-withfthatz'iof.'

said .beat frequency oscillator to produce-aydi fference frequency, and means for indicatlng;.,the.-

presence of the various difference frequencies... I 2; vIn. an arrangement fordetenniningthepresencaof and direction to 1 a.-,.source of Qradianten-a erggjy; a plurality of radiantenergy -receiying' .mentsof. the .typegcontainingya capacitivecdevice and means. "for ,varying'ithe. capacity of said Lea-z.

pactive device in accordance with variations: .im the intensity ofreceiVed radiant. energy,--;radi' 1.I-1t..v

energy collectingandlfocussingmeansgmeansapo:

sitioningpaidreceivlnggelements 'along angaxis n... lenent-eeifl mllegtla are However, acommonr. fixed. oscillator 4 l .is. :employed kinstead' of-;.three=.: separate fixed .oscillators,': shownin .Fig; 1; its utput being fed .to. mixers I 8, l 8', and I! :to. zero beat with .each; of radio-frequency".varyingc; oscillators I5, I5 and..l5'- to .derive a difference- For example two more channels. may be addedto indicate targets above andbelowv focussingmeans whereby received radiant energy is concentrated at a point along said axis 7 determined by the direction of the received radiant energy, an individual variable frequency oscillator for each of said receiving elements, each of said variable frequency oscillator circuits containing as a frequency varying element the capacitive device of its associated receiving element whereby the frequency of each variable fre quency oscillator is determined by the intensity of the radiant energy received by its associated receiving element, a mixer circuit individual to each variable frequency oscillator, a fixed frequency oscillator, means for applying the output of each variable frequency oscillator to its associated mixer circuit and for applying the output of said fixed frequency oscillator to each of said mixer circuits whereby a difference frequency appears in the output of each of said mixer circuits upon receipt ofradiant energy by the, corresponding receiving element, and means connected to the output of each mixer circuit to indicate the presence of a difference frequency.

JACOB S. HERSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS n Date 

